Method and arrangement for processing mobile station history information in a wireless communication system

ABSTRACT

Methods and apparatus for processing mobile station transaction information at a serving control node in a wireless communication system are disclosed. The serving control node may be a base station, such as an eNodeB in an LTE/SAE wireless communication system. The transaction information, which may include, for example, mobility-related transaction information and traffic-related transaction information for a given mobile station, may be passed between controlling control nodes as the corresponding mobile station is handed over, so that a controlling control node has access to information characterizing the past activities of the mobile station. This information may be used in some embodiments for selecting a target control node for handover or for allocating link resources.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/597,559, filed Feb. 18, 2010, pending, which was the National Stageof International Application No. PCT/SE07/51050, filed Dec. 20, 2007,which claims the benefit of Swedish Application No. 0701010-1, filedApr. 26, 2007, the disclosure of which is incorporated herein byreference.

BACKGROUND

1. Technical Field

The present invention generally relates to wireless communications, andparticularly relates to methods and apparatus for processing mobilestation transaction information among base stations in a wirelesscommunication system employing a distributed control architecture.

2. Background

As wireless network operators strive to increase the capacity andthroughput of their networks, it is expected that cells in mobilecommunication systems will be deployed in a wide variety of sizes. Inparticular, many cells will be much smaller than in past systems.Network operators are already beginning to extensively deploy so-calledmicro-cells and pico-cells in, for example, shopping centers, citycenters, and office areas.

At the same time, there is a trend to move radio network controlfunctionality to the base station site in new network architectures.This is true, for example, in the Long Term Evolution (LTE) wirelesscommunication systems currently under development by the3^(rd)-Generation Partnership Project (3GPP). Similar concepts are alsobeing discussed with respect to the implementation of very small RadioNetwork Controllers (RNCs) for Evolved High-Speed Packet Access (HSPA)systems. Proponents of this trend suggest that locating resource controlfunctionality at the base station site will result in better systemperformance, because more timely information will be available for radioresource management decisions.

On the other hand, network control procedures implemented in acentralized architecture, such as handover procedures in a conventional3G RNC, can more readily exploit information regarding the situation inseveral neighboring cells as well as conditions in the current cellwhere a user equipment (UE) is located. The use of a distributedarchitecture, i.e., a system model where control functionality is pushedto the base stations, thus potentially creates a situation where thecontrol function has a great deal of up-to-date knowledge of the localenvironment, but does not have the broader network overview that mightbe available in a centralized control function. In such a system, ahandover procedure performed at an LTE base station (an eNodeB) might bebased largely on limited information, such as status information for thecurrent cell and any neighboring cells served by the same eNodeB.

Another potential problem with a distributed architecture model is thatmobile user equipment may be controlled by several different controllersover a short period of time, as the user equipment is passed (handedover) from one base station to another. Although each controller (theeNodeB in the case of an LTE system) can monitor the activity of aspecific mobile station while serving that mobile station, thisinformation is generally lost when the mobile station is handed over toanother controller. This is less of a problem in a system using acentralized control architecture, since a controller in such a systemtypically covers many cells, and a mobile station is generallycontrolled by the same controller for a longer period of time.

SUMMARY

The present invention comprises methods and apparatus for processingmobile station transaction information at a serving control node in awireless communication system. In particular, the serving control nodemay be a base station node, such as an eNodeB in an LTE/SAE system. Thetransaction information which may include, for example, mobility-relatedtransaction information and traffic-related transaction information fora given mobile station, may be updated and passed between controllingcontrol nodes as the corresponding mobile station is handed over, sothat a controlling control node has access to information characterizingthe past activities of the mobile station. The transaction information,which may be passed from one control node to another in the form of atransaction history record, may include, by way of non-limiting example,information about the cells in which the mobile station has beenpresent, and for how long, as well as information describing the mobilestation's uplink and downlink data transfer activity.

Among the advantages provided by the inventive methods and apparatusdisclosed herein are that a control node in accordance with one or moreembodiments of the invention thus has access to historical transactioninformation for a served mobile station, which may be used, in variousembodiments, to improve link resource allocation decisions, to improvehandover decisions, and to detect and/or prevent undesirable handoverpatterns, including so-called ping-pong handovers. Those skilled in theart will appreciate further advantages resulting from the timely,comprehensive, and up-to-date historical information made available byseveral embodiments of the present invention.

Accordingly, an exemplary method comprises receiving, at a servingcontrol node, a transaction history record from a transferring controlnode in association with a first handover of a mobile station to theserving control node. After adding mobile station transaction datarelated to the serving control node to the transaction history record toobtain an updated transaction history record, the updated transactionhistory record is transferred to a target control node in associationwith a subsequent handover of the mobile station to the target controlnode. In some embodiments, the method further comprises using thetransaction history record to make handover decisions, such as selectinga target control node for a handover, or for allocating link resources.

Embodiments of the invention further include a control node configuredto carry out one or more of the methods described for processing mobilestation transaction history data. One or more of these control nodeembodiments may comprise an eNodeB for use in an LTE/SAE network.

In still other embodiments, a computer program product includescomputer-readable program code embodied on a computer-readable medium,the computer readable program code being configured to carry out one ormore of the above-described methods.

Of course, the present invention is not limited to the above featuresand advantages. Indeed, those skilled in the art will recognizeadditional features and advantages upon reading the following detaileddescription, and upon viewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating aspects of an LTE/SAE wirelesscommunication network.

FIG. 2 illustrates exemplary mobile station transaction information andits relationship to cells of a wireless communication system.

FIG. 3 is a logic flow diagram of one embodiment of a method forprocessing mobile station transaction information.

FIG. 4 is a logic flow diagram of another embodiment of a method forprocessing mobile station transaction information.

FIG. 5 is a block diagram of one embodiment of a base station configuredto process mobile station transaction information.

DETAILED DESCRIPTION

The design and specification of the next generation of wirelesscommunication networks is currently ongoing under the auspices of the3^(rd)-Generation Partnership Project (3GPP), in an effort known as theLong Term Evolution (LTE) initiative. Along with the definition of newwireless interfaces, a new core network architecture is also beingdefined, in a standardization effort referred to as System ArchitectureEvolution (SAE). As shown in FIG. 1, an LTE/SAE network includes atleast two types of network elements supporting user and control planes:an enhanced base station 110, called the Evolved NodeB or “eNodeB”; andthe SAE Gateway 120. The eNodeB 110 provides the LTE air interface andradio resource management, while the SAE Gateway 120 provides a mobilityanchor point for the user plane and provides a gateway to IP servicenetworks 140, which may include the Internet, intranets, and otherIP-based service networks.

In the discussion that follows, the present inventive methods andapparatus are described in the context of an LTE/SAE wireless network.In this case, many of the control functions described herein reside inan eNodeB 110. However, those skilled in the art will appreciate thatthe inventive techniques described herein are applicable to othernetwork types and other network configurations. For example, theinventive methods and apparatus disclosed herein may be applicable to anevolved High-Speed Packet Access (HSPA) architecture, in which the RadioNetwork Controller (RNC) is integrated into the NodeB, as well as to aRelease 99 GERAN/UTRAN architecture, in which the history informationdescribed below might be transferred between peer control nodes (e.g.,RNCs and/or Base Station Controllers). Thus, the description of theinvention in terms of LTE/SAE network elements is meant to beillustrative, not limiting.

Unlike its predecessors, the LTE/SAE architecture does not include aseparate Radio Network Controller (RNC) responsible for managing severalbase stations. Instead, many of the radio resource management andmobility management functions previously performed by a RNC are moved tothe eNodeB 110. As noted above, this move allows the control function toaccess more timely information regarding the radio resource conditions(e.g., signal conditions, loading conditions) at the one or severalcells served by the eNodeB 110. However, this move also presents somechallenges, as an eNodeB 110 generally lacks the broader system overviewthat an RNC monitoring several base stations might have.

Control decisions made with only local information can create severalproblems. For instance, a rapidly moving mobile station (such as mobilestation 160 in FIG. 1) in a distributed architecture might be handedover between several micro-cells (generating frequent handovers), whenthis mobile station 160 might be better served by a macro-cell in thesame area. A control function located at one of these severalmicro-cells may be unaware that that the mobile station 160 is movingrapidly, or that the mobile station 160 has recently encounteredfrequent handovers.

As another example, an inactive mobile station 160 should after someperiod of time be moved into a more power-efficient state. In adistributed architecture, there is a risk that a mobile station 160moving across the network is never controlled by a single controller fora sufficiently long period of time for the controller to recognize thatthe more power-efficient state should be triggered.

Other problems may arise upon handover in system with distributed radioresource management. For instance, if a mobile station 160 is handedover from one base station to another in the middle of an ongoing uplinkdata transfer, it would be preferred that the mobile station 160immediately receive an adequate allocation of uplink resources in thetarget cell, even before the mobile station 160 sends an uplink bufferstatus report to the target eNodeB 110. This is difficult to achieve ina distributed architecture if the resource control function at thetarget cell is unaware of the level of mobile station activity in theold cell. These challenges potentially result in wasted radio resourcesor unnecessarily constrained mobile station performance.

Thus, the present disclosure is directed to methods and apparatus foruse in a wireless communication system, in which a controller unit,e.g., a radio resource control function in an LTE eNodeB 110, maintainsa transaction history for a mobile station 160 and passes that historyto subsequent controller units that receive control of the mobilestation 160. The transaction history contains information about the pastactivities of the user equipment. In some embodiments, the transactionhistory includes mobility-related transaction information, such asinformation about the cells in which the mobile station 160 has beenpresent and the time spent in those cells. In some embodiments, thetransaction history includes traffic-related information, such as thequantity and/or type of data traffic sent to and/or received by themobile station 160.

In an exemplary embodiment of the present invention, a resourcecontroller currently serving a mobile station 160, e.g., the radiocontrol function at the serving eNodeB 110, passes transaction historyinformation for the mobile station 160 to the resource controller thatwill take over control of the mobile station 160 after handover, e.g.the radio control function at the target eNodeB 110. In variousembodiments, this transaction history information may take any ofseveral forms. For instance, the transaction history may comprise ahistorical list that lists events added by each controller that hascontrolled the mobile station 160. Alternatively (or in addition to saidlist), the transaction history may comprise one or several cumulativeparameters describing the past mobility and activity level of the mobilestation 160. These cumulative parameters may be updated by each controlfunction as the mobile station 160 is handed over from one base stationto another.

In some embodiments, the controller, when taking control of a mobilestation 160 by means of an incoming handover, receives a transactionhistory record from the previous control function, and uses thetransaction history information as input to subsequent decisionprocesses. For instance, the controller may use traffic-relatedtransaction information from the transaction history record inallocating resources to the mobile station 160. This traffic-relatedtransaction information might include data rates, data quantities,and/or data types recently transmitted or received by the mobile station160. The controller might also use mobility-related transactioninformation from the transaction history record, including informationidentifying previous cells and previous cell types visited by the mobilestation 160 and the time spent at each. A controller might use this typeof information, for example, in selecting a target cell for a subsequenthandover. For instance, if the historical mobility-related transactioninformation indicates that the mobile station 160 has been frequentlyhanded over, the controller might determine that a macro-cell is a moreappropriate handover target than an adjacent micro-cell.

In several embodiments, a serving controller might add additionaltransaction information, and/or update cumulative parameters concerningthe mobile station's activity, for passing on to a subsequent controllerwhen performing a subsequent handover.

The transaction history record might be defined with a parameterindicating a maximum size for the record, to control the size of therecord that is forwarded at each handover. In some such embodiments,controllers might apply a first-in-first-out strategy when the size ofthe transaction history record exceeds the predetermined maximum size,deleting the oldest information to make room for newer information. Inother embodiments, information might be stored in the record inassociation with a time stamp, so that transaction information thatexceeds a certain age, i.e., information that has been in the record forgreater than a predetermined time, is removed from the transactionhistory.

Generally, but without excluding other types of information, the contentof the transaction history may be divided into at least two categories.The first, mobility-related transaction information, comprisesinformation related to previously-visited cells. This category ofinformation might include, among other things, a cell identity, celltype, and time spent in a cell (or a mobile terminal entry time and/ormobile terminal departure time), for each of several previously visitedcells. FIG. 2 illustrates an example of the mobility-related transactioninformation that might be contained in a transaction history record. InFIG. 2, cell IDs c002, c028, and c014 identify micro-cells 210 coveringan area partly covered by a macro-cell 220, corresponding to a cell IDof C017. Exemplary mobility-related transaction information 230 is alsopictured.

The receiving controller can use the historical information included intransaction information 230 together with other information, such asmobile station measurements, to take decisions regarding the mostsuitable target cell or system. For example, a radio resource controllerusing the mobility-related transaction information 230 of FIG. 1 mightconclude that a mobile station 160 coming from cell c002 and havingstayed there for less than a certain period of time, such as 120seconds, should be handed over to the macro cell C017 if mobile stationmeasurements indicate that this is feasible.

The receiving controller may also use this information to estimate otherparameters. For example, if the controller has information on theaverage neighbor cell sizes, it might use transaction historyinformation indicating the time spent in previous cells to produce arough speed estimate for the mobile station 160. Referring once more tothe mobility-related transaction information shown in FIG. 2, a mobilestation 160 that stayed for 84 seconds in cell c028, perhaps having aradius of only 100 meters, might be designated as a “medium-speed” user.

Mobility-related transaction information might also be used to generateand update cumulative parameters that describe a mobile station'smobility. For instance, a running parameter indicating the number ofhandovers per time unit or an estimated mobile station velocity might beupdated by each controller before the transaction history record isforwarded to a new controller. Optionally, these parameters might beweighted or filtered, so that recent mobility information is effectivelyranked higher than older information.

A second category of transaction history data is traffic-relatedtransaction information. This category might include information such aswhen the mobile station 160 entered an active mode and/or trafficactivity (optionally, with time stamps) during the active mode. Trafficactivity information might identify specific bearers that have been usedby the mobile, the last time when a packet was sent, the quantity ofdata sent or received, the types of data sent or received, and so on. Insome embodiments, data relating to various activities may betime-stamped with a time parameter calculated with reference to thestarting time of an active mode. This approach can reduce the amount ofdata stored in the transaction record, and eliminates the need fortime-stamps to be recalculated at each handover.

Referring again to FIG. 2, an exemplary set of traffic-relatedtransaction information 240 is illustrated. Those skilled in the artwill appreciate that the mobility-related and traffic-related data ofFIG. 2 is illustrative only. As explained above, various data might berecorded at each base station. Furthermore, the information may berecorded in a variety of formats; appropriate coding of the informationmay reduce the size of the data that is transferred between basestations. In any event, in some embodiments of the present invention, areceiving controller can use the traffic-related transaction information240, perhaps in conjunction with mobility-related transactioninformation 230, to make various resource management decisions. Forinstance, the controller might use the information to determine when totrigger a transition of the mobile station 160 to a more power-efficientstate. As an example, the receiving controller might receive thetraffic-related transaction information 240 in conjunction with ahandover of a mobile station 160. After 1590 milliseconds from themoment that the mobile station 160 entered into the cell, the controllermight trigger a transition to idle state. This example assumes aninactivity timer of 6000 milliseconds, which was triggered because thecontroller could calculate that the mobile station 160 had already beeninactive for 4410 milliseconds (4560 minus 150).

As was described earlier with respect to mobility-related transactioninformation, a radio resource controller can generate and/or update oneor more cumulative parameters describing a mobile station's trafficactivity, for inclusion in the transaction history record passed fromcontroller to controller. These cumulative parameters might include, forexample, an average uplink and/or downlink bit rate, for a given timeperiod or for the duration of an active mode period. Cumulativeparameters indicating peak uplink or downlink requirements for themobile station 160 might also be maintained. Any of these parametersmight be weighted or filtered, so as to rank more recent activityinformation higher than older information.

Accordingly, a transaction history record for a mobile station 160,containing any of the above information, may be passed from atransferring base station to a serving base station, in a first handoverof the mobile station 160. After updating the transaction historyrecord, the serving base station may transfer the updated transactionhistory record to a target base station in association with a subsequenthandover of the mobile station 160. This general procedure isillustrated in FIG. 3, which may be implemented, for example, in aneNodeB 110 of an LTE/SAE wireless communication system. Those skilled inthe art will appreciate that some of the steps illustrated in FIG. 3 maybe omitted. Furthermore, several of the steps may be performed in adifferent order than shown.

At block 310, a transaction history record for a mobile station 160 isreceived from a transferring base station. In some embodiments, thetransaction history is received in association with a handover of themobile station 160 to a new serving base station. The transactionhistory record may be transferred directly, as part of thehandover-related messaging between the transferring and new serving basestation, or it may be transferred indirectly, such as through a separategateway or server. In an LTE/SAE system, for example, the transactionhistory may be transferred between the base stations using the X2interface defined by 3GPP.

At block 320, control of the mobile station 160 is received from thetransferring mobile station 160. With the exception of the transfer ofthe transaction history record, handover may be performed according toconventional means. Those skilled in the art will appreciate thatcontrol of the mobile station 160 by the receiving base station may beobtained prior to receiving the transaction history record in someembodiments and/or under certain circumstances.

At block 330, the receiving base station (now the serving base station)adds mobility-related transaction data to the transaction historyrecord. This may comprise simply adding a cell identifier correspondingto the serving base station, perhaps with a time stamp indicating thetime spent at the receiving base station. This latter information, ofcourse, cannot be finally added to the transaction history record untilthe mobile station 160 is handed over to a new base station. Othermobility-related transaction data, such as any of the items discussedabove, may be added to the transaction history record as well.

At block 340, the serving base station adds traffic-related transactiondata to the transaction history record. This may comprise anyinformation characterizing data transfers performed while the mobilestation 160 is served at the current cell, such as any of thedata-related parameters discussed above. In some embodiments, asdiscussed earlier, parameters describing particular data transfer eventsmay be added; these parameters may characterize a quantity or type ofdata transfer, and may include time stamp information. In someembodiments, the traffic-related transaction information added to thetransaction history record may include only a time-stamp indicating whena mobile station 160 last transmitted or received data; in otherembodiments, the traffic-related transaction information willcharacterize data transfers in great detail.

At block 350, one or more cumulative activity parameters are updated.This updating may require that a cumulative parameter be retrieved fromthe transaction history record, modified, and then saved in a newlyupdated transaction history record. These cumulative activityparameters, as noted above, may include parameters characterizing themobile station's mobility, such as a parameter indicating the totalnumber of handovers for a mobile station 160, or the number of handoversper a particular reference time period, or parameters characterizingdata traffic activities, such as a maximum downlink or uplink datatransfer, or an average rate of data transfer per a reference timeperiod.

Finally, at block 360, the updated transaction history record istransferred to a target base station. This may be in association with ahandover of the mobile station 160 to the target base station, asillustrated at block 370.

As noted above, the transaction history record corresponding to a mobilestation 160 may be used by a serving base station to make radio resourcecontrol decisions related to that mobile station 160. The serving basestation might, for instance, allocate link resources (such as resourceblocks, in an LTE/SAE system) for the mobile station 160 based at leastin part on traffic-related transaction information contained in thetransaction history record. Further, a serving base station might basehandover decisions on the transaction history record.

FIG. 4 thus provides an illustration of an exemplary method for using atransaction history record, as might be implemented, for example, in aneNodeB 110 of an LTE/SAE wireless communication system. The method ofFIG. 4 “begins” at block 410 with the receipt of a transaction historyrecord corresponding to a mobile station 160 under the control of (orabout to be transferred to) a base station. Generally, the transactionhistory record is transferred directly from a transferring base station,although indirect transfers are possible. Those skilled in the art willappreciate that some of the steps illustrated in FIG. 4 may be omitted.Furthermore, several of the steps may be performed in a different orderthan shown.

At block 420, the receiving (now serving) base station predicts linkresource requirements for the mobile station 160 based on thetransaction history record. In some embodiments, the transaction historyrecord may be available to the base station before a transmit bufferupdate is received from the newly transferred mobile station 160, andmay be used to allocate link resources or update a previously madeallocation of link resources, as shown at block 430. In someembodiments, the transaction history record may be used in conjunctionwith buffer information received from the mobile station 160 ordetermined at the base station to predict the resource requirementslikely to be associated with the mobile station 160. Thus, someembodiments of the present invention provide the advantage of improvedlink resource allocation based on improved prediction of resourcerequirements for a served mobile station 160.

At block 440, the serving base station uses the transaction historyrecord to identify cells previously visited by the mobile station 160.The transaction history record thus facilitates improved handoverdecisions, as this information may be used for, among other things,selecting a target base station, as shown at block 450. Thepreviously-visited cell information may be used, for example, to reduceso-called ping-pong handovers, where a mobile station 160 is repeatedlyhanded over between two neighboring cells. Thus, in some embodiments,the previously-visited cell information is evaluated to detect a patternof ping-pong handovers. If a pattern of ping-pong handovers, or otherundesired handover pattern, is detected, then the serving base stationmay adjust one or more handover criteria in response. For instance,handover criteria may be adjusted so that a serving base station holdson to a mobile station for a longer time before handing over. (Thoseskilled in the art will appreciate that this may be accomplished inseveral ways. For instance, one or more signal strength thresholds forhandover may be adjusted.) Alternatively, a mobile terminal may behanded over from a micro-cell to a macro-cell in response to detecting aping-pong pattern or other undesired handover pattern. Detection of anundesired handover pattern may also trigger the generation of adiagnostic message for use by system operators in troubleshooting andmaintaining the system. This diagnostic message may be saved in a log,or sent to a designated address for a system operator.

Similarly, the previously-visited cell information may be analyzed todetermine whether a mobile station 160 currently served by a micro-cellmight be better served by an overlapping macro-cell. This determinationmight be based, for instance, on the number of micro-cells visited in agiven time period, so that rapidly moving mobile terminals experiencefewer handovers.

At block 460, in preparation for an imminent handover, the transactionhistory record is updated, as discussed above in reference to FIG. 3.Finally, at block 470, the updated transaction history record istransferred to the target base station, again as discussed earlier.

Referring now to FIG. 5, an exemplary base station 500 that may be usedto implement one or more of the methods described herein is pictured.Those skilled in the art will appreciate that the illustrated basestation 500 is just one example of a control node for implementing themethods described herein. Many of the functions of control processor510, in particular, may be implemented using a separate device, whichmight be co-located with conventional base station equipment or locatedremotely from the base station. Thus, the control node functionality maybe part of an eNodeB in an LTE/SAE system, for example, or may be aseparate control function in any other network. For instance, asdiscussed above, the control node functionality may be part of a radionetwork controller (RNC) or a base station controller. Thus, a controlfunction may be associated with a single base station or several basestations.

In any event, the exemplary base station 500 of FIG. 1 includes aprocessing unit 510 configured for communication with one or more mobilestations 160 using radio transceiver circuitry 520 and antenna 525. Basestation 500 further includes a network interface 570 for communicationwith other elements of a wireless network, including, in someembodiments, other base stations 500 and access gateways such as theLTE/SAE access gateways 120 pictured in FIG. 1. Those skilled in the artwill appreciate that in some embodiments base station 500 may comprisean eNodeB for use in an LTE/SAE wireless communication system, but theinventive methods and apparatus described herein are applicable to otherwireless network standards and other network configurations as well.Generally speaking, radio transceiver circuitry 520 and portions of theprocessing unit 510, such as baseband signal processor 530, areconfigured to comply with one or more wireless telecommunicationsstandards, such as those promulgated by 3GPP. For instance, by way ofnon-limiting example, baseband signal processor 530 may be configured toencode and decode signals in accordance with 3GPP LTE standards definingphysical layer protocols for Orthogonal Frequency Division MultipleAccess (OFDMA)-based downlink signals and Single Carrier FrequencyDivision Multiple Access (SC-FDMA) uplink signals.

Processing unit 510 includes, in addition to baseband signal processor530, a radio resource manager 540, mobility manager 550, other controlprocessing 555, and memory 560, which in turn comprises a program store562 and other data needed for operation of the base station 500,including transaction history data 564. Those skilled in the art willappreciate that FIG. 5 depicts a functional representation of theelements of processing unit 510. Accordingly, each of the picturedprocessing blocks may in some embodiments directly correspond to one ormore commercially available or custom microprocessors, microcontrollers,or digital signal processors. In other embodiments, however, two or moreof the functional blocks of 510 may be implemented on a singleprocessor, while functions of other blocks are split between two or moreprocessors. Likewise, memory 560 is representative of the one or morememory devices containing the software, firmware, and data used toimplement base station functionality in accordance with one or moreembodiments of the present invention. Thus, memory 560 may include, butis not limited to, the following types of devices: cache, ROM, PROM,EPROM, EEPROM, flash, SRAM, and DRAM.

Base station 500, and in particular, processing unit 510, may beconfigured to implement one or more of the methods described herein forprocessing mobile station transaction information. Accordingly,processing unit 510 may be configured to receive a transaction historyrecord from a transferring base station in association with a firsthandover of a mobile station 160 to base station 500. The transactionhistory record is typically received through network interface 570,which in an LTE system may comprise an X2 interface as defined by 3GPPspecifications. The processing unit 510 is further configured to addmobile station transaction data to the transaction history record; thismobile station transaction may include mobility-related transactioninformation and/or traffic-related transaction information as describedearlier. Processing unit 510 is further configured to transfer theupdated transaction history record to a target base station inassociation with a subsequent handover of the mobile station to a targetbase station.

In some embodiments, processing unit 510 may be configured to identifypreviously visited cells for a mobile station using the correspondingtransaction history record, and to select a target base station for thesubsequent handover based, at least partly, on the previously-visitedcell information. In such embodiments, then, mobility manager 550, whichis generally responsible for handover-related functions, uses thecontents of the transaction history record for a given mobile station160 to make handover-related decisions. In some embodiments, processingunit 510 may estimate a speed for the mobile station 160, based oninformation included in the transaction history record, and may use thatestimated speed in handover decisions. Thus, mobility manager 550 maydetermine that a particular mobile station 160 is better served by amacro cell than by a micro-cell, based on the transaction history data.

Similarly, the radio resource manager 540, which allocates linkresources between multiple mobile stations 160, may use transactionhistory data to make resource allocation decisions. The transactionhistory record for a newly received mobile station 160 may be used, forexample, to make or adjust link resource allocations in advance ofreceiving a transmit buffer update from the mobile station 160. Thetransaction history record may also be used in conjunction with statusinformation received from the mobile station 160 for making linkresource allocations.

Computer program code for carrying out operations of the various controlnodes discussed above with respect to FIGS. 1-5 may be written in ahigh-level programming language, such as Java, C, and/or C++, fordevelopment convenience. In addition, computer program code for carryingout operations of embodiments of the present invention may also bewritten in other programming languages, such as, but not limited to,interpreted languages. Some modules or routines may be written inassembly language or even micro-code to enhance performance and/ormemory usage. It will be further appreciated that the functionality ofany or all of the program modules may also be implemented using discretehardware components, one or more application specific integratedcircuits (ASICs), or a programmed digital signal processor ormicrocontroller.

The present invention was described above with reference to flowchartand/or block diagram illustrations of methods, devices, and/or computerprogram products in accordance with some embodiments of the invention.These flowchart and/or block diagrams thus illustrate exemplaryoperations for processing mobile station transaction information inaccordance with various embodiments of the present invention. It will beunderstood that each block of the flowchart and/or block diagramillustrations, and combinations of blocks in the flowchart and/or blockdiagram illustrations, may be implemented by computer programinstructions and/or hardware operations. These computer programinstructions may be provided to a processor of a general purposecomputer, a special-purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing the functionsspecified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerusable or computer-readable memory that may direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstructions that implement the function specified in the flowchartand/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions that execute on the computer or other programmableapparatus provide steps for implementing the functions specified in theflowchart and/or block diagram block or blocks.

As will be appreciated by those skilled in the art, the foregoingdescription and the accompanying drawings represent non-limitingexamples of the methods and apparatus taught herein. As such, thepresent invention is not limited by the above description andaccompanying drawings. Instead, the present invention is limited only bythe following claims and their legal equivalents.

What is claimed is:
 1. A method for processing mobile stationtransaction information at a serving control node in a wirelesscommunication system, the method comprising: receiving a transactionhistory record from a transferring control node in association with afirst handover of a mobile station to the serving control node; addingmobile station transaction data related to the serving control node tothe transaction history record to obtain an updated transaction historyrecord; transferring the updated transaction history record to a targetcontrol node in association with a subsequent handover of the mobilestation to the target control node.
 2. The method of claim 1, whereinthe mobile station transaction data comprises mobility-relatedtransaction information or traffic-related transaction information orboth.
 3. The method of claim 1, wherein the transaction history recordcomprises identifiers for one or more cells visited by the mobilestation before arriving at the serving control node.
 4. The method ofclaim 1, wherein adding mobile station transaction data related to theserving control node to the transaction history record to obtain anupdated transaction history record comprises adding a cellidentification parameter for the serving control node and one or more ofa cell descriptor and one or more time parameters indicating a length oftime for which the mobile station was served by the serving controlnode.
 5. The method of claim 4, wherein the cell descriptor indicates acell type or a cell size or both.
 6. The method of claim 1, whereinadding mobile station transaction data related to the serving controlnode to the transaction history record to obtain an updated transactionhistory record comprises adding at least one traffic activity parameter.7. The method of claim 6, wherein the at least one traffic activityparameter indicates one or more of a data bearer type, a data quantity,a data rate, and a data activity time.
 8. The method of claim 1, whereinadding mobile station transaction data related to the serving controlnode to the transaction history record to obtain an updated transactionhistory record comprises updating one or more cumulative parametersincluded in the transaction history record.
 9. The method of claim 1,wherein the method further comprises selectively removing one or moredata items from the received transaction history record based on the ageof the one or more data items.
 10. The method of claim 1, wherein themethod further comprises selectively removing one or more data itemsfrom the received transaction history record based on the size of thetransaction history record and a predetermined maximum size for thetransaction history record.
 11. The method of claim 1, wherein themethod further comprises identifying previously visited cells for themobile station using the transaction history record and selecting thetarget control node for the subsequent handover based on the previouslyvisited cells.
 12. The method of claim 1, wherein the method furthercomprises: identifying previously visited cells for the mobile stationusing the transaction history record; evaluating the identifiedpreviously visited cells to detect one or more undesired handoverpatterns; and selecting the target control node for the subsequenthandover based on said evaluation and the previously identified cells.13. The method of claim 12, wherein the one or more undesired handoverpatterns include a ping-pang handover pattern characterized by repeatedhandovers between two base stations, wherein selecting the targetcontrol node for the subsequent handover based on said evaluation andthe previously identified cells comprises adjusting one or more handovercriteria in response to detecting said ping-pong handover pattern. 14.The method of claim 12, wherein the method further comprises generatinga diagnostic message in response to detecting one or more of theundesired handover patterns.
 15. The method of claim 1, wherein themethod further comprises determining an estimated speed for the mobilestation using the transaction history record and selecting the targetcontrol node for the subsequent handover based on the estimated speed.16. The method of claim 1, wherein the method further comprisespredicting a link resource requirement for the mobile station based onthe transaction history record and allocating link resources based onthe predicted link resource requirement.
 17. A first control node foruse in a wireless communication system, the first control node includinga processing unit, wherein the processing unit is configured to: receivea transaction history record from a transferring control node inassociation with a first handover of a mobile station to the firstcontrol node; add mobile station transaction data related to the firstcontrol node to the transaction history record to obtain an updatedtransaction history record; transfer the updated transaction historyrecord to a target control node in association with a subsequenthandover of the mobile station.
 18. The first control node of claim 17,wherein the mobile station transaction data comprises mobility-relatedtransaction information or traffic-related transaction information orboth.
 19. The first control node of claim 17, wherein the transactionhistory record comprises list of cells visited by the mobile stationbefore arriving at the first control node.
 20. The first control node ofclaim 17, wherein the first control node comprises a base station nodein the wireless communication system.
 21. The first control node ofclaim 17, wherein the first control node comprises a radio networkcontroller (RNC) in the wireless communication system.
 22. The firstcontrol node of claim 17, wherein the first control node comprises abase station controller (BSC) in the wireless communication system. 23.The first control node of claim 17, wherein the processing unit isconfigured to add mobile station transaction data related to the firstcontrol node to the transaction history record to obtain an updatedtransaction history record by adding a cell identification parameterassociated with the first control node and one or more of a celldescriptor and one or more time parameters indicating a length of timefor which the mobile station was served by a cell corresponding to thecell identification parameter.
 24. The first control node of claim 23,wherein the cell descriptor indicates a cell type or a cell size orboth.
 25. The first control node of claim 17, wherein the processingunit is configured to add mobile station transaction data related to thefirst control node to the transaction history record to obtain anupdated transaction history record by adding at least one trafficactivity parameter.
 26. The first control node of claim 25, wherein theat least one traffic activity parameter indicates one or more of a databearer type, a data quantity, a data rate, and a data activity time. 27.The first control node of claim 17, wherein the processing unit isconfigured to add mobile station transaction data related to the firstcontrol node to the transaction history record to obtain an updatedtransaction history record by updating one or more cumulative parametersincluded in the transaction history record.
 28. The first control nodeof claim 17, wherein the processing unit is further configured toselectively remove one or more data items from the received transactionhistory record based on the age of the one or more data items.
 29. Thefirst control node of claim 17, wherein the processing unit is furtherconfigured to selectively remove one or more data items from thereceived transaction history record based on the size of the transactionhistory record and a predetermined maximum size for the transactionhistory record.
 30. The first control node of claim 17, wherein theprocessing unit is further configured to identify previously visitedcells for the mobile station using the transaction history record and toselect the target control node for the subsequent handover based on thepreviously visited cells.
 31. The first control node of claim 17,wherein the processing unit is further configured to determine anestimated speed for the mobile station using the transaction historyrecord and to select the target control node for the subsequent handoverbased on the estimated speed.
 32. The first control node of claim 17,wherein the processing unit is further configured to predict a linkresource requirement for the mobile station based on the transactionhistory record and to allocate link resources based on the predictedlink resource requirement.
 33. The first control node of claim 17,wherein the processing unit is further configured to: identifypreviously visited cells for the mobile station using the transactionhistory record; evaluate the identified previously visited cells todetect one or more undesired handover patterns; and select the targetcontrol node for the subsequent handover based on said evaluation andthe previously identified cells.
 34. The first control node of claim 33,wherein the one or more undesired handover patterns include a ping-panghandover pattern characterized by repeated handovers between two basestations, wherein the processing unit is further configured to adjustone or more handover criteria in response to detecting said ping-ponghandover pattern.
 35. The first control node of claim 33, wherein theprocessing unit is further configured to generate a diagnostic messagein response to detecting one or more of the undesired handover patterns.36. A non-transitory computer program product for use in or with acontrol node in a wireless communication system, the non-transitory,computer program product comprising computer-readable instructionsoperable, when executed by a processor, to: receive a transactionhistory record from a transferring control node in association with afirst handover of a mobile station to the serving control node; addmobile station transaction data related to the serving control node tothe transaction history record to obtain an updated transaction historyrecord; and transfer the updated transaction history record to a targetcontrol node in association with a subsequent handover of the mobilestation to the target control node.